Direct pressed laminated flooring (DPL) usually comprises a core of a 6-12 mm fibre board, a 0.2 mm thick upper decorative surface layer of laminate and a 0.1-0.2 mm thick lower balancing layer of laminate, plastic, paper or like material.
The surface layer of a laminate floor is characterized in that the decorative and wear properties are generally obtained with two separate layers one over the other. The decorative layer is generally a printed paper and the wear layer is a transparent overlay paper, which comprises small aluminium oxide particles.
The printed decorative paper and the overlay are impregnated with melamine formaldehyde resin and laminated to a wood fibre based core under heat and pressure.
Recently new “paper free” floor types have been developed with solid surfaces comprising a substantially homogenous mix of fibres, binders and wear resistant particles. Such floors are referred to as WFF (Wood Fibre Floor).
The wear resistant particles are aluminium oxide particles, the binders are thermosetting binders such as melamine formaldehyde and the fibres are wood based. In most applications decorative particles such as, for example, colour pigments are included in the homogenous mix. All these materials are mixed together and applied in dry form as a mixed powder on a core, generally a HDF core, and cured under heat and pressure to a 0.1-1.0 mm solid surface layer.
Several advantages over known technology and especially over conventional laminate floorings can be obtained. The wear resistant surface layer, which is a homogenous mix, can be made much thicker and a wear resistance is achieved, which is considerably higher. New and very advanced decorative effects can be obtained with deep embossing and by separate decorative materials, which can be incorporated into the homogenous surface layer and coordinated with the embossing. An increased impact resistance can be reached with a homogenous surface layer, which is thicker than a paper based laminate surface and which may have a higher density. The homogenous surface layer can comprise particles that have a positive impact on sound and moisture properties. Production costs can be reduced since low cost and even recycled materials can be used and several production steps can be eliminated.
Powder technology is very suitable to produce a decorative surface layer, which is a copy of stone or ceramics. It is also possible to create wood designs and other advanced designs with high definition digital printers that use a non-impact printing processes. The digital printer has print heads, generally so called Piezo heads, that “fire” drops of ink from the print heads and into the powder based substrate prior to pressing. Digital printing may be used to obtain the complete design or to just to add a wood grain structure to powder that already comprises a basic colour.
The quality of the powder-based surface is to a large extent affected by the mixing of the different materials and the application of the powder mix on the core. These two production steps are also usually the most costly and crucial parts of the production process.